The present invention relates to a method and circuit device for checking an optical cable for the passage of light and undue increases in attenuation caused by defects, with the attenuation per unit length of an identical undamaged optical fiber cable being known.
An installed optical cable is customarily composed of a series of individual cable length units (e.g., each 1 km in length). After installation of each cable length unit, it is necessary to check the entire cable, including the last installed length unit, for the passage of light and to determine precisely whether the installed cable has unduly high attenuation caused, e.g., by a break in a conductor or a defective splice or plug-in connection.